The balance wheel is the heart of your automatic watch.  The oscillation of the balance wheel is the “heart beat”.  The balance wheel “beats” or oscillates at a controlled rate or frequency. 

When a watch receives shock, the travel of the balance wheel is disrupted.  The period of time it takes to return the balance wheel to it’s normal “beating” is lost accuracy.  Even the simple task of clapping your hands causes a disruption of your balance spring  and affects accurate time-keeping.

 High-frequency or ocillating movements recover more quickly and lose less time. But watches that run at a higher frequency have more work to do in the same period of time, which means breakdown and wear on components.

The best answer to reduce the effect of shock on the movement is to stabilize the balance wheel through shock protection.

 “The most stable regulating organ – not the fastest – will enable the watch to keep more accurate time.”

-Ryan Schmidt, Quill and Pad


When a watch receives a severe shock dial feet can sheer off, pivots of wheels can break, screws can become loose and bridges can shift.  All of these outcomes severly affect the time keeping of the watch and may result in catastrophic failure.

The watch industry provides testing guidlines for what it considers severe shock.  The fundamental requirement of ISO 1413 is that an automatic watch, falling 1m (3.28ft) onto a hardwood floor, should maintain accuracy within a range of +/- 60 seconds/day. 

There are two major issues with ISO 1413.  First, the force of a 1m drop onto a hard wood floor is approximately 5000 G's.  While this number may seem impresssive, high G-forces can be generated easily by common solid objects falling insignificant heights onto hard surfaces.  While large forces over a long period of time (a fighter pilot maneuver) result in lower “G” numbers.  The force of a golf swing on your wrist is approximatley 5000 G's. . . hardly a "high-shock" event.

Second, a watch passing ISO 1413, need only be accurate to +/- 60 seconds per day.  An automatic watch with these specs would be considered broken and in need of repair.

ISO 1413, clearly, is not rigourous enough.


Traditionally, mounting movements in watches involved screws and/or a solid metal ring or brace. These casing methods do nothing to reduce the shock transmitted to the movement at impact and may even increase the shock transmitted.  According to research presented by Rolex,

“Various tests, including those undertaken by the applicant, have revealed that these casing-up solutions not only transmit a shock from the case to the movement, but also amplify it.  Accordingly, a cased-up movement in a watch which experiences a shock of 10,000 g will be subjected to a shock of 25,000 g, that is to say amplified by a factor of 2.5.” - Victor Marks, A BLOG TO WATCH

SEAHOLM has incorporated cutting edge materials designed to replace the traditional screw-down casing method and mitigate the impacts of shocks.   Our shock mount is made of a visco-elastic polymer.  Visco-elastic material displays characteristics of both elastic (solid) and viscous (liquid) materials.  Unlike rubber, steel, plastics or other elastic substances, visco-elastic materials deform under stress and return to shape slowly. This slow return to shape most efficiently dissipates energy.  Our visco-elastic shock mount, dramatically reduces the impact of shocks on the movement by 83%.  


Anti - Magnetic

Seven times the anti-magnetic protection compared to other automatic watches.


Water Resistance

All SEAHOLM® Watches are tested to ISO 6425; Diver's water resistant standards.



Learn More About


I was staking out my yard before the Everglades Seafood Festival and my 3-pound sledge hammer slipped off the stake and hit squarely on the case of my Offshore. Without my Seaholm, I would have broken my wrist, probably surgery.  Not only did my Offshore save my wrist but still looks great and works perfectly.  Now that’s shock proof!

Geoff Q.